Diagnosis of kidney and urinary tract infections is often facilitated by a knowledge of the patient's urinary flow rate. Urinary flow rate data is particularly important in critical care situations, and in particular when the patient has just undergone surgery since the patient may not be conscious and able to verbalize any symptoms. In critical care situations, urine is usually continuously drained from the body via a Foley type catheter and the urine output is usually determined by visually observing the amount of urine drained from the patient via the catheter into a drainage receptacle.
Examples of prior art drainage receptacles for enabling the quantity of urine drained via a Foley type catheter to be determined are found in U.S. Pat. Nos. 4,301,813, 4,095,589, 4,085,616 and 4,000,649. Each of the prior art drainage receptacles described in the above listed patents includes a transparent urine receiving chamber having a graduated scale thereon for indicating the quantity of urine entering the chamber. The urine flow rate is determined in such devices by observing the quantity of urine entering the chamber of the drainage receptacle over a period of time.
While the prior art devices are satisfactory for this purpose, there are several disadvantages associated with measuring urine in this manner. The most obvious disadvantage is that the urine flow is detected visually. This requires either a nurse, a doctor or a technician to observe the patient for a set period of time. In practice, a nurse generally records the volume of urine at 15 minute intervals. However, inaccuracies may arise due to failure to maintain an exact interval between observations. In addition, an exact measurement may not always be obtained due to the imprecisions in reading the drainage receptacle scale. More importantly, the use of prior art urine flow measuring techniques do not provide an instantaneous measure of excessive urine output unless the nurse, doctor or technician is present to observe the excessive urine output.